Using the javascript library jQuery and delving into its copious amount of plugins (autocomplete example link below) would enable you to have a responsive AJAX interface for a text-entry box.
You wouldn't need django-piston to get the AJAX aspect of what I mention above to work, but it somewhat simplifies getting results in a JSON format, and allows you to easily add in new API calls at a later date with its familiar format (well, familiar once you get used to it).
Links: django-piston: http://bitbucket.org/jespern/django-piston/wiki/Home
jQuery: http://jquery.com/
jQuery autocomplete example: http://www.pengoworks.com/workshop/jquery/autocomplete.htm
AJAX definition: http://en.wikipedia.org/wiki/Ajax_(programming)
JSON definition: http://en.wikipedia.org/wiki/JSON